Mountain Thornbill Acanthiza katherina Scientific name definitions

The Mountain Thornbill is a threatened, range-restricted, and rather little-known inhabitant of upland rainforest in the Wet Tropics of northern Queensland, Australia. Its appearance and behavior are rather charismatic—its constant and abrupt motions while foraging may be reminiscent of a wind-up toy, and its large-headed and fluffy physique is very cute—but it is also a denizen of the canopy with a nondescript plumage, and can be challenging to see well. Many observers consider it little more than another "Little Brown Job." For this reason, the Mountain Thornbill does not attract as much attention as do some other avian endemics of the Wet Tropics, such as the Victoria's Riflebird (Ptiloris victoriae) or Golden Bowerbird (Prionodura newtoniana). Hence, many elementary questions about the Mountain Thornbill's life history remain unanswered. Its begging calls, for instance, are undescribed, while the first detailed treatment of its other vocalizations is presented in this publication. Many opportunities remain for enterprising ornithologists to expand our collective knowledge of this species.

Of particular interest to evolutionary biologists and ethologists is the fact that the Mountain Thornbill, although classified consistently in a clade of pair-breeding thornbill species, is at least occasionally (and probably almost always) a cooperative breeder, indicating that cooperative breeding has likely arisen multiple times in the genus Acanthiza. The reasons for this occurrence—particularly in light of the general scarcity of cooperative breeding among birds—remain incompletely understood.

As with most of the Wet Tropics' many other endemic taxa, avian and otherwise, climate change appears to pose a significant risk to the Mountain Thornbill's long-term survival. Drastic population declines in recent years are already well documented (1 Williams, S. E., and A. de la Fuente (2021). Long-term changes in populations of rainforest birds in the Australia Wet Tropics bioregion: A climate-driven biodiversity emergency. PLOS ONE 16(12):e0254307. Close ). The cool and moist conditions necessary for the health of this species' habitat are already yielding to hotter weather, longer droughts, and a higher frequency of extreme weather events. One study found that Mountain Thornbill abundance at certain ecological restoration sites may exceed its abundance in primary forest, which perhaps provides a ray of hope for the future, but that result is exceptional (2 Freeman, A. N. D., C. P. Catterall, and K. Freebody (2015). Use of restored habitat by rainforest birds is limited by spatial context and species’ functional traits but not by their predicted climate sensitivity. Biological Conservation 186:107–114. Close ). Unfortunately, as matters stand at present, the Mountain Thornbill appears to be placed firmly on the so-called "Escalator to Extinction" (3 Freeman, B. G., M. N. Scholer, V. Ruiz-Gutierrez, and J. W. Fitzpatrick (2018). Climate change causes upslope shifts and mountaintop extirpations in a tropical bird community. Proceedings of the National Academy of Sciences of the United States of America 115:11982-11987. Close ).